Introduction
Corneal dystrophies are a group of rare eye diseases that are often:
- Inherited
- Progressive
- Affect both eyes equally
- Do not affect other areas of the body
- Are not brought about by external factors, e.g. diet or injury
- Start in one layer and can spread to other corneal layers
- Not linked to diseases in other body or eye parts
- Occur in healthy individuals
Corneal dystrophy is an eye disorder in which a section or sections of the cornea lose clarity because of accumulation of cloudy matter. All corneal dystrophies cause an abnormal accumulation of foreign material in the cornea. Over time, the patient’s vision may become blurry or cloudy.
Corneal dystrophies differ in the way they affect vision. Some lead to severe visual impairment, while others don’t affect vision. Yet, others may cause recurrent pain without leading to irreversible vision loss.
Superficial or anterior corneal dystrophies often begin before the age of 20. It may take many years before they affect the patient’s vision. The most common type in this category is epithelial basement membrane dystrophy, also known as map-dot-fingerprint dystrophy.
Stromal corneal dystrophies often start in childhood or in teen age. Some types may impact the patient’s vision within a few years. Others may take decades before their effect is noticed. The most common type in this group is the lattice dystrophies.
Many of the posterior corneal dystrophies appear early on in life, at times at birth. Fuchs’ endothelial corneal dystrophy is the most common in this category. It starts in the patient’s 40’s or 50’s. It may take decades before it causes vision problems.
Also Known As
CDs
Sub-Types
There are over 20 different types of this eye condition. They are often grouped into three broad categories.
- Superficial or anterior corneal dystrophies
This group occurs on the outside layers of the cornea.
These include:
- Lisch corneal dystrophy
- Epithelial basement membrane dystrophy
- Reis-Bucklers corneal dystrophy
- Thiel-Behnke corneal dystrophy
- Meesmann corneal dystrophy
- Stromal corneal dystrophies
These affect the middle and thickest layer of the cornea.
This category includes:
- Lattice corneal dystrophy
- Gelatinous drop-like corneal dystrophy
- Macular corneal dystrophy
- Granular corneal dystrophy
- Schnyder crystalline corneal dystrophy
- Posterior corneal dystrophies
These manifest in the interior parts of the cornea.
This group includes:
- Fuchs’ endothelial corneal dystrophy
- Congenital hereditary endothelial dystrophy
- Posterior polymorphous corneal dystrophy
Causes and Risk Factors
Most types of corneal dystrophy are genetic. And, most cases of the corneal dystrophy are autosomal dominant; meaning only one parent needs to have the gene for the child to be affected.
A few forms of the disorder are autosomal recessive; both parents must have the gene for the condition.
The risk factor is a family history of the disease.
Signs & Symptoms
Symptoms depend on the type of corneal dystrophy. They vary from utterly asymptomatic to vision loss.
The common symptom of corneal dystrophy is a cloudy or blurry vision.
The others include:
- Watery eyes
- Foreign object feeling in the eye
- Sensitivity to light
- Dry eyes
- Pain in the eye
- Corneal erosions
- Glare
Diagnosis
Corneal dystrophy may be detected during a routine eye exam. The eye professional can conduct a comprehensive examination to confirm the diagnosis. The evaluation may include a detailed patient history and a variety of tests including slit lamp examination and genetic testing.
Treatment
Treatment focuses on relieving the symptoms.
Medical Treatment
Treatment depends on the type of corneal dystrophy, the symptoms, the rate of progression and a patient's health and quality of life.
Watchful waiting is adopted where the individual is asymptomatic or has mild symptoms. The eye doctor may recommend regular eye checkups to track the disease.
In other cases, including those involving repeat corneal erosion, the doctor may prescribe special contact lenses, artificial tears, ointments, eye drops or antibiotics.
Surgical Treatment
Where the corneal erosion persists, the doctor may recommend laser therapy or surgery to scrape the cornea.
Severe cases may need a corneal transplant. It is a common and highly successful procedure which removes the unhealthy cornea and replaces it with a clear and healthy cornea obtained from a donor.
In fact, many types of corneal dystrophy need corneal transplant to restore vision.
Alternative Treatment
Prognosis/Long-term outlook
Many types of corneal dystrophy can lead to loss of vision.
Genetic counseling may be beneficial for the patients and their families.
Where there is a family history of the disease, an individual should get regular eye checks.
Prevention/Follow Up
Corneal dystrophies are genetic in origin, meaning there are no preventive measures.
Routine eye exams can help diagnose the disorder. Treatment should begin immediately if necessary.
